A power converter for a hybrid system of an automobile controls motor current by switching of a power semiconductor device. With increase in the output from the hybrid system in recent years, motor current and voltage of the system are increasing. Therefore, the problem of surge voltage generated at the time of switching of the power semiconductor device has been an issue to overcome.
Conventionally, surge voltage generated by switching is decreased by reduction of main circuit inductances of the power semiconductor device and a capacitor achieved by shortening the wiring lengths of the power semiconductor device and the capacitor and laminating the wirings thereof, and laminating the wirings inside the capacitor, or by other methods (for example, see PTL 1). The reduction of surge voltage allows high-speed switching and thus achieves reduction of losses, so that the fuel cost of the vehicle can improve.